1. Field of the Invention
A process and apparatus to reclaim polystyrene-type polymer material.
2. Description of the Prior Art
Resin and plastic products such as molded products or foamed products of natural or synthetic resins permeate contemporary life. Unfortunately such resins are almost never decomposed by microorganisms. When such resins are burnt, toxic gases are generated which may corrode the furnace. Thus the disposal of waste resin products has become a serious problem. Some attempts at regenerating a resin from waste resin products have been proposed. For a polystyrene resin or the like, a method has been proposed wherein a waste polystyrene resin is burnt to be gasified and the gasified resin is separated to allow recovery of the resin. However, as may be apparent from this example, a process for reprocessing a waste resin and regenerating a resin therefrom requires a considerable investment in facilities and a high running cost. This process also results in a high energy consumption and has therefore not been frequently adopted in practice.
U.S. Pat. No. 4,104,341 shows a process for the manufacture of fibrids by dissolving, in a solvent, macromolecular waste materials from the bead polymerization of styrenes and introducing the solution into a precipitation medium under the action of shearing forces to form fibrids.
U.S. Pat. No. 4,164,484 discloses a process for classifying plastic-containing wastes by dissolving a mixture of plastics containing polyolefin-type plastics in a hydrocarbon solvent at a temperature between 60 and 80 degrees C., then vacuum-evaporating the solvent of the solution to cause precipitation of the polyolefin-type plastics dissolved therein, separating and recovering the major portion of the precipitate. The resulting separated solution is divided into the concentrated liquor of the precipitate remaining admixed in the separated solution and the phase of a solution containing the precipitate. The concentrated liquor is reused to dissolve the mixture of plastics. The solvent is removed from the phase of a solution hardly containing the precipitate so as to recover the polystyrene-type plastics. The process comprises connecting in series a plurality of solid-liquid separating devices, sequentially disintegrating and dispersing the precipitate separated by the separating device at a preceding stage in the separated solution flowing out from the separating device at a subsequent stage and again separating the precipitate by the separating device at a still subsequent stage.
U.S. Pat. No. 4,196,105 shows a process and apparatus for separating and recovering polystyrene with sulfur dioxide. The polystyrene is dissolved to form two phases, an upper phase which contains the polystyrene and a lower phase which contains the sulfur dioxide solvent which is practically free from polystyrene which can be reused. The polystyrene is recovered from the upper polystyrene containing phase by boiling off the sulfur dioxide.
U.S. Pat. No. 4,517,312 shows a process for regenerating a resin comprising the steps of dissolving a waste resin in an organic solvent to provide a resin solution, mixing the resin solution to provide a resin solution with a liquid of normal temperature, the liquid being immiscible with the solvent, scarcely dissolving the resin, and having a specific gravity less than that of the solvent and greater than that of the resin thereby separating the resin from a mixture of the resin solution and the liquid and recovering the resin. The liquid may have a temperature higher than the boiling point of the solvent. In this case, the solvent evaporation takes place together with the resin separation. The evaporated solvent is cooled later for recovery.
U.S. Pat. No. 4,857,587 shows a continuous flow process for the production of high impact polystyrene wherein specific types of polymerization inhibiting impurities are removed from the recycle stream prior to feeding or introducing the recycle stream into a styrene polymerization zone.
Additional examples of the prior art are disclosed in U.S. Pat. No. 3,311,675; U.S. Pat. No. 4,255,372 and U.S. Pat. No. 4,451,583.